1. Field of the Invention
The present invention concerns a rotor of a compression-wave engine comprising cells arranged uniformly distributed over its periphery and oriented parallel to the rotor axis, which are intended in operation to receive two gaseous media with the aim of compressing the first medium with compression waves of the second.
2. Discussion of Background
When they are used as supercharger for internal combustion engines, in compression-wave engines ambient air is compressed to supercharging air, and when they are used as high-pressure compressor stage of a gas turbine supercharged air is further compressed in order to generate working gas for the high-pressure turbine component. In this connection, the compression of the air takes place in a rotor, whose periphery in present-day designs generally has cells extending axially parallel, in which the air comes directly into contact, without a fixed separating element, with the exhaust gas of the engine or with working gas branched off from the turbine combustion chamber. In order to control the inlets and outlets of air and gas into, or out of, the cells, casings with passages for the supply and/or removal of the two media participating in the compression-wave process are located on the two end faces of the rotor. When a cell filled with air to be compressed comes before a high-pressure gas inlet, a compression wave runs into the cell and compresses the air. The compression wave reaches the end of the cell as soon as the latter passes the high-pressure air outlet. The air is expelled there, and the cell is then completely filled with gas. Upon further rotation, expansion waves ensure that the gas once again leaves the cell and that fresh air is sucked in, whereupon the compression process is repeated.
A critical circumstance, which contributes decidedly towards the delivery efficiency of a compression-wave blower, consists in that the surface of discontinuity between the two media of air and gas is by no means perpendicular to the axis of the passage, but that a more or less wide mixing zone is formed there, whereby during the scavenging of the compressed air, gas passes into the engine or into the turbine circulation, on the one hand, and a part of the air passes over into the gas, on the other hand.
What has been said above also happens due to the known fact that when two media of different density which have firstly been separated from one another by a diaphragm are located in a passage, upon removal of this diaphragm a balancing flow is set in train, under the influence of gravity in the case of media at rest, apart from the complete mixing of the two gaseous media, as occurs in the state of rest.
In the case of a compression-wave engine, when the rotor is running the heavier medium, that is to say air, is thrust out of the engine under the lighter exhaust gas by the centrifugal acceleration at the outside of the cell, resulting in a mixing zone which is very wide by comparison with the state of rest and, as mentioned above, worsens the scavenging and, consequently, the delivery efficiency of the blower.